One specimen of 2 mm of the very rare sulphate-nitrate mineral humberstonite from the TL in Chile (Oficina Alemania, Santa Catalina, Antofagasta Province, Antofagasta Region, Chile) in a capsule. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Humberstonite
Humberstonite is an IMA-recognized mineral species in the nitrate class, with the chemical formula K₃Na₇Mg₂(SO₄)₆(NO₃)₂·6H₂O.
It crystallizes in the hexagonal crystal system (space group R-3).
Key properties: Mohs hardness 2.5; specific gravity 2.252; Vitreous luster; optically uniaxial.
IMA symbol Hbe, IMA status: approved, named in 1967.
Formed by repeated natural leaching of nitrate ore with reprecipitation in irregular pods above the local regolith.
It is found associated with Blödite, nitratine, kieserite.
The mineral was named to honor James Thomas Humberstone (1850–1939), industrial chemist whose contributions permit economical extraction of nitrate from the Chilean deposits.